docs: def label_count(self):
          """
          Return for each label the number of occurrences within the list.
  
          Returns:
              dict: A dictionary containing for every label-value (key)
              the number of occurrences (value).
  
          Example:
              >>> ll = LabelList(labels=[
              >>>     Label('a', 3.2, 4.5),
              >>>     Label('b', 5.1, 8.9),
              >>>     Label('a', 7.2, 10.5),
              >>>     Label('b', 10.5, 14),
              >>>     Label('a', 15, 18)
              >>> ])
              >>> ll.label_count()
              {'a': 3 'b': 2}
          """
  
          occurrences = collections.defaultdict(int)
  
          for label in self:
              occurrences[label.value] += 1
  
          return occurrences